The reduced damage of the ability scales linearly with channel time [2]. For example, cancelling after 1.5 seconds will deal around 50% of the full damage, cancelling after 0.1 seconds will deal around 12.5%, and cancelling after 2.9 seconds will deal around 87%.

Absolute Zero's area of effect is only visible to enemies if they have vision of Nunu. If he is in the Fog of War or in brush while channeling, enemies will not see the spell animation but they can still be affected by it.